Three-dimensional (3d) displays have become very important for many applications including vision research, operation of remote devices, medical imaging, surgical training, scientific visualization, virtual prototyping, and more. It is important in these applications for the graphic image to create a faithful impression of the 3d structure of the object or scene being portrayed. Unfortunately, 3d displays often yield less perceived depth or even distorted percepts compared with real scenes. Additionally, the uncoupling of vergence and accommodation required by 3d displays frequently causes viewer discomfort and fatigue. We received four years of funding to investigate these problems with conventional 3d displays and to develop new displays to minimize those problems. We achieved all of the stated goals and now seek funding to continue the technical development of the display and to use it to conduct basic and applied vision research. There are five Specific Aims. 1. Continue the construction, development, and evaluation of multi-plane 3d displays using the switchable lens technology developed in the first grant period. 2. Investigate how blur and accommodation affect stereopsis. Examine how the ability to binocularly fuse and interpret complex images is affected by the correlation between disparity-specified depth and blur and accommodative signals. Investigate the role of blur and accommodation in the perceived distortions observed with stereoscopic photographs and cinema. Develop more accurate models of these phenomena based on the experimental results. 3. Investigate the role of blur and accommodative signals in the perception of size and distance. Examine how the orientation of the blur gradient relative to the depth gradient affects the so-called tilt-shift miniaturization effect. Examine how variation in blur relative to local depth variations and how active accommodation affect size and distance perception. 4. Re-examine some well-known effects in the structure-from-motion and shape-from-shading literatures to determine if they are caused in part by conflicting blur and accommodative information. If they are, develop more accurate models of these phenomena based on the experimental results. 5. Evaluate the benefits of providing stereoscopic and near-correct focus cues in a medical-imaging application. Assess the ability to track fibers in white-mater tracts from DTI data using 2d, conventional 3d, and multi-plane 3d displays. Measure perceptual accuracy, time required, and visual fatigue and discomfort in the three types of displays. PUBLIC HEALTH RELEVANCE The proposed research will investigate the perception of displayed visual information. It involves the construction and evaluation of new display technology, optics techniques, and graphics methods. All of these technical developments will be useful in creating three-dimensional displays with near-correct focus cues which would allow the users of virtual reality to see the 3d structure of simulated scenes more correctly. This would have clear benefit for many uses of virtual reality such as medical imaging, minimally invasive surgery, telesurgery, medical training, and scientific visualization. This may also yield side benefits such as correction for presbyopia.